1. Field of the Invention
The present invention relates to a video detecting device and a method thereof, and more particularly, to a video detecting device and method for detecting sawtooth and field motion.
2. Description of the Prior Art
Conventional interlaced scan techniques display odd scan lines and even scan lines in an image frame one after the other when displaying the image frame. Hence, each frame is actually composed of two interlaced fields—one odd field composed of the odd scan lines and one even field composed of the even scan lines.
The modern progressive scan technique, also called the non-interlaced scan, however, merges two fields into a frame, and then sequentially scans the frame at a doubled horizontal scan frequency thereby increasing the stability and precision of the appearance of a picture.
Since there may be a time difference between images of different fields, detecting if there is image motion between two fields that are to be merged (i.e. field motion) before merging the fields into the frame is an important task. If field motion does exist between the two fields, sawtooth will appear in the frame when merging the fields into the frame, thereby deteriorating picture quality.
The detecting method for detecting field motion and sawtooth in a conventional video detecting device usually cannot identify the variations in dynamics and static in high-frequency regions precisely, such as that proposed in the U.S. patent of application Ser. No. 10/904,454. Therefore, the precision of the output picture in high-frequency circumstances is greatly influenced.